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Marita P Feldkaemper, Sandra Bernhard-Kurz, Frank Schaeffel; Time of the day influence of exposure to intense illuminance and inherent variability of intense illuminance on the development of experimentally induced myopia in chicks.. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5528.

Purpose :
Low frequency cycles of bright light (1 min bright light:1 min room light) have been shown to inhibit the development of deprivation myopia more effectively than exposure to continuous high illuminance. In the present study, we tested whether the effect of bright light on negative lens compensation can also be improved by modulating the temporal features. It is also known that the sensitivity of eye growth to retinal image degradation varies over the day. We therefore compared the effect of bright light given in the morning to bright light exposure in the evening.

Methods :
Chicks wore -7D lenses unilaterally, while the contralateral eye remained open. Paradigm I: 300 lux at a 10:14 light:dark cycle. Paradigm II: Continuous bright light (14000 lux) for 5 h in the morning and 300 lux for the next 5 hours. Paradigm III: Intermittent episodes of bright light for 10 h. Paradigm IV: same as paradigm III, cage covered with white cardboard. White Leghorn chicks wore a diffuser unilaterally. Paradigm V: 14000 lux 5 h in the morning followed by 300 lux. Paradigm VII: 300 lux for 5 h in the morning, then 14000 lux 5 h. Refraction was measured prior to and after the 4 day experiment. Six animals per group were used. Changes were analyzed by un-paired t-tests.

Results :
Intermittent episodes of high illuminance did not inhibit the development of lens-induced myopia more effectively than continuous light. Overall, the bright light exposure slowed compensation of minus lenses down in only 50% of experiments. Covering of the cage with white cardboard (paradigm IV) increased the inhibitory effect of bright light on myopia significantly. Bright light exposure reduced the amount of deprivation myopia development significantly more when the exposure occurred in the morning than in the afternoon (refraction at day 4 in the diffuser treated eye:-3.13D ± 0.71D vs. -6.54D ± 0.84D).

Conclusions :
The effects of bright light on minus lens compensation are inherently variable. Intermittent exposure to bright light in combination with covering the cages with white cardboard was most effective. High illuminance inhibited the development of deprivation myopia more if the treatment occurred in the morning. There is a need to determine the variables that control the inhibitory effect of high illuminances on experimentally induced myopia in more detail.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.